1. Field of Invention
The present invention relates to an apparatus and a method for driving an interlaced plasma display panel (PDP). In particular, it relates to an apparatus and a method for driving an interlaced PDP capable of reducing flickers at the upper edge and the lower edge of an image.
2. Description of the Related Art
In general, the time for displaying images of an interlaced plasma display panel (PDP) can be divided into an even field and an odd field. The even field displays the image signal of even scan lines, and the odd field displays the image signal of odd scan lines. The even field and the odd field are displayed one after the other.
Referring to FIG. 1, it is a timing chart of even field signal in a conventional PDP. Wherein, Scan0, Scan2 and Scan4 are scan signals from a scan side driver, corresponding to the scan lines 0, 2 and 4, respectively. Scani indicates a scan signal of odd scan lines, and Scanj indicates a scan signal of even scan lines. Common indicates a common signal from a common side driver. Data indicates a data signal from a data side driver. The axis of time in FIG. 1 is divided into three periods by four vertical dotted lines, namely a reset period 101, an address period 102 and a sustain discharge period 103, respectively. As shown in FIG. 1, since the address period 102 is an even field, scan pulses appear in the scan signals of even scan lines only. Thus, the even scan lines light up, and the odd scan lines don't.
FIG. 2 is a timing chart of odd field signal in a conventional PDP. Since the address period 202 in FIG. 2 is an odd field, scan pulses appear in the scan signals of odd scan lines only. Thus, the odd scan lines light up, and the even scan lines don't.
In a conventional interlaced driving mode, the alternate display of odd scan lines and even scan lines would result in flickers at the upper edge and the lower edge of an image to affect the visual effect. Please refer to FIG. 3. Suppose the PDP has 720 scan lines, marked with numbers 0 to 719, then the first scan line 304 (number 0) only lights up in an even field, and the last scan line 303 (number 719) only lights up in an odd field. Consequently, the even field image 301 and odd field image 302 are alternatively displayed, so human eyes would detect flickers.
The U.S. Pat. No. 6,169,527 introduces a method, where black, opaque shades are added at the uppermost area and the lowermost area of a display region to prevent the flickers in the interlaced driving mode. But, when the upper edge and the lower edge of the image are not the upper edge and the lower edge of the panel, for example, when displaying the popular 16:9 images by 4:3 displays, the flickers remain.
Thus a better method is desired to prevent the above-described flickers when the upper edge and the lower edge of the image are not the upper edge and the lower edge of the panel.